Internal combustion engine



April 10, 1934. L. M. WOOLSON 1,954,113

I INTERNAL COMBUSTION ENGINE I Filed Oct. 10, 1929 2 Sheets-Sheet. 1

gwwmto'a L1 UNEL M. N001, sum- 10, 1934- L. M. w oLsou 1,954,113

INTERNAL COMBUSTION ENGINE Filed Oct. 10, 1929 2 Sheets-Sheet. 2

Patented Apr. 10, 1934 UNITED STATES PATENT OFFICE 1,954,113 INTERNALCODIBUSTION ENGINE Application October .10, 1929, Serial No. 398,619

16 Claims.

This invention relates to internal combustion engines, and moreparticularly to engines of the type in which explosions occur throughthe heat of compression.

With the type of engine referredto, it is obvious and well-known thatstarting is difficult due to the temperature of the cylinders being muchlower than that required to cause combustion of the fuel introducedtherein. When such engines are used for aeronautical purposes, I havefound that when a cylinder stops firing during flight, which occursusually when gliding or when the fuel supply is reduced, then the airwhich is of a lower temperature than combustion temperature tends tochill such missing cylinder, and renewal of firing is difficult toaccomplish. Both of these conditions are undesirable and become morepronounced as lower temperatures are encountered.

It is an object of this invention to utilize compression ratio changingmechanism for increasing the heat development in the cylinders so thatthere will be a higher compression ratio when the engine is underlighter loads and vice versa, such mechanism also serving to increasethe volume of the airsupply conversely with elevation, within cruisinglimits when used as the power plant for airplanes.

' Another object of my invention is to provide an internal combustionengine of the type set forth in which the temperature within thecylinders is automatically regulated inversely to the quantity of fuelin the combustion charge.

A further object of my invention is to provide an internal combustionengine, of the compression ignition type in which fuel and air areintroduced separately into the cylinders, having automatically actuatedmechanism for maintaining a constant horse power in different elevationswith a given quantity of injected fuel.

Still another object of my invention is to provide an aeronauticalengine in which the compression ratio is automatically regulated by andinversely relative to the engine load, whereby the lowest ratio ispresent under the greatest load" and 'vice versa. 1 I

Another object of the invention is to provide an .internal combustionengine with a compression ratio changing device which will also absorbthe explosion shocks ordinarily transmitted to and absorbed by the crankshaft.

Other objects of the invention will appear from the followingdescription taken in connection with the drawings forming a part of thisspecification, in which:

Fig. 1 is a rear elevation of an engine, partially broken awayandpartially in section, with which the invention is incorporated,

Fig. 2 is a section view of the same taken on line 2-2 of Fig. 1,

Fig. 3 is a perspective view of the eccentric and counterweight elementof the compression ratio changing mechanism,

Fig. 4 is a fragmentary sectional view taken on line 4-4 of Fig. 2.

Referring to the drawings by characters of ref- .6! erence, 10represents a barrel type of crank case for an internal combustion engineof the Diesel type, in which liquid fuel and air are introducedseparately into the working chambers and ignited by the heat developedby compression in the cyl- 7C inders. Extending radially from the casingare a plurality of cylinders 11 which are secured rigidly to the casing,pistons 12 being arranged to ,reciprocate in the cylinders. .The casingis divided" into three aligned compartments 13, 14, and 15, 76 theforward compartment 13 providing a lubricating oil reservoir, the endcompartment 15 providing a housing for mechanism actuating the cylindervalves and the fuel'pumps, while the central compartment,'which alignswith the cyl- 80 inders, is the crank case proper.

The central axial portion of the crank case is formed as a hub for thereception of a single throw counterbalanced crank shaft 16, suitablebearings 173 18, and 19, being arranged intermediate the hub and thecrank shaft. Secured to the forward end of the crank shaft is anaeroplane propeller 20 which the engine illustrated is designed torotate. The design of the propeller obviously is an important factor indetermining the engine load, as the engine develops only the load whichthe propeller will absorb, and such loads vary with propeller design.

The cylinder heads are provided with a single port 21 through which airis drawn during the suction stroke, the engine illustrated being of thefour-cycle type, and such ports are also utilized as the exhaust outlet,although separate valves for the inlet and exhaust can be employedequally as well A valve member 22 is arranged 1m to control the innerend of each port, such valves being unseated by rocker arms 23 actuatedby rods 24 and normally closed by the springs 25. Suitable mechanism,intermittently operated from the shaft, is employed to unseat the valverods in the desired sequence. A high pressure liquid fuel injectiondevice is associated with each cylinder to spray fuel into thecylinders, each of such devices consisting of a pump portion 26 and anozzle or atomizing portion 27, the pumps be- 11 ing intermittentlyactuated through rods 28 operated from the crank shaft by suitablemechanism in desired sequence, and adjustable to vary the quantity offuel injected as desired. Air is first injected into the cylinders, andthen during compression thereof, liquid fuel issprayed into thecylinders, combustion taking place through the heat of compressioncaused-by the operation of the pistons. The operation, and the detailsof the structure so far described, are fully set forth in my Patent No.1,896,387, issued February '7, 1933. It will be understood that a highspeed engine capable of running above 1500 R. P. M. is required foraeronautical purposes, and the engine illustrated will operate abovesuch speed and is designed to sustain flight when running atapproximately 1400 R. P. M.

.The pistons are connected to the crank pin 29 through a master rod 30and connecting rods 31 pivotally mounted in circular relation around thehub of the master rodby pins 32, such connections being conventionalwith radial engines. Ordinarily, however, the master rod is mountedconcentrically upon the crank pin and the com pression ratio is definedand unchangeable.

In order to assist starting or bringing in of cylinders which haveceased firing during flight or otherwise, I propose to associatemechanism with the master rod and crank shaft so that the compressionratio is automatically varied inversely with and by the load on theengine.

As a means for accomplishing such results, I provide an eccentricbushing or sleeve 33 intermediate the hub of the master rod and thecrank pin, such sleeve being rotatable relative to both the master rodand crank pin and being arranged intermediate the crank cheeks. Thecrank end center of the master rod structure is shown at A, and as thispoint is eccentric to the axis B of the crank pin, an increase in loadwill actuate the master rod structure to move the eccentric sleeve 33 ina clockwise direction looking from the cockpit, asshown by the arrow onthe crank pin in Fig. 1, thereby shifting the position of the master rodrelative to the crank pin to decrease the compression ratio. Lookingfrom the front of the aeroplane, the crank shaft rotates anti-clockwisewhile the eccentric rotates anti-olockwise to decrease the compressionratio and clockwise to increase the compression ratio; In the structureshown the compression ratio range is preferably 20 to 1 at the maximumand 10 to l at the minimum, the piston strokes being shorter with thelower ratio and longer with the higher ratio.

In order to prevent actuation of the eccentric until predetermined loadsare present in the engine, and to resist the movement of the eccentricfrom a position providing a maximum high compression ratio, I providemechanism which I have preferably associated with the crank shaft. Tothis end, the eccentric sleeve is provided with a flange 34 at one endhaving teeth 35 formed in the periphery thereof. The end of the crankshaft adjacent the sleeve flange is bored axially to accommodatemechanism for resisting movement of the sleeve to decrease thecompression ratio, and for returning the sleeve to normal position asthe load decreases. A rod 36 extends through the bore of the shaft andisforrned with a gear 37 exteriorly of the crank cheek and meshes withthe teeth of the eccentric flange. A member 38, functioning as aretainer and bearing member for the rod, is screwed into the end of thebore in the crank cheek, and a carriage 39 having an interior wormgroove is mounted to reciprocate in the shaft bore, the carriage havinglugs 40 engaging in grooves 41 in the crank shaft to prevent rotationthereof. The rod is formed with a worm 42 engaging the carrier wormgroove so that upon rotation of the rod, through its meshing relationwith the eccentric sleeve flange, the carriage will be reciprocated. Inorder to oppose sleeve rotation in a direction reducing the compressionratio, a coil spring 43 is arranged in the crank shaft bore andencircling the rod.

A shaft extension 44 is screwed into the forward end of the crank shaftbore and carries internally a pair of bearing members 45 and 46intermediate which packing 47 is arranged. The spring 43 extends betweenand bears against the carriage 39 and the bearing 45 and adjustment ofthe extension 44 determines the tension of the spring which can thusberegulated as desired. The rod extends through the shaft extension anda thrust bearing 52 and a retainer nut 53 and lock nut 54 are screwedupon the threaded end of the rod extending through the thrust bearing.The member 38 and the thrust bearing flx the rod longitudinally, butallow rotation thereof; a bearing member 55 retains the propeller on theshaft and is retained by a sleeve 56 which screws upon.

the shaft extension, such sleeve also serving as a starter clutch. Whenthe shaft extension is adjusted so that it does not engage the end ofthe crank shaft, then retaining means therefor will, be required.

Adjustment of the sleeve 44 will regulate the spring compression, and inthis instance a pressure of 2000 pounds is exerted by the spring inopposition to movement of the carriage. With aeronautical engines it isdesirable that the spring be regulated so that the eccentric sleeve willnot rotate until the R. P. M. is such that the engine will sustainflight, which in this instance is approximately 1400 R. P. M. Thus, itwill be seen that the spring serves to automatically return theeccentric to high compression relation as the load falls off, and to actas a resistance which will permit movement of the eccentric to lower thecompression ratio only as the load increases sufliciently to overcomethe same. When the spring is fully compressed, the compression ratio isat its lowest point, and in this manner the lowest ratio of the rangecan be determined as desired for different engines and conditions. Itwill be seen, therefore, that the compression ratio will beautomatically varied with the load, and that when idling, or with fuelinjection charges of smaller quantities, the load will not overcome thespring thus maintaining a high compression ratio which causes thecylinders to become warmer than when the compression ratio is low,whereby such increased heat is transmitted to the fuel mixture thereinwhich will promote combustion heat and consequently assist starting andbringing in of cold cylinders. The spring tension is overcomeproportionately to the load the propeller imposes on the engine, thusallowing movement of the carriage and rotation of the rod and eccentricsleeve so that lower compression results thereby reducing pressure andtemperature in the cylinders.

The spring 43 furthermore, serves as a vibration damper, as explosiveshocks which ordinarily are transmitted to the crank shaft will beabsorbed thereby.

As previously described, the master rod center A is eccentricallyarranged relative to the center of the crank pin B during the entirerange of the compression ratio device movement, and when the master rodcenter moves relative to the crank iii pin center, the centrifugal forceof rotation will result in an unbalanced engine. In order to overcomesuch unbalanced condition, a weight 50 is mounted opposite the rodeccentric point of mounting to bring about equilibrium of the master rodrelative to the crank pin so that there is no movement of the center ofgravity of the compression ratio changing device in its range ofmovement relative to the crank shaft. The weight 50 is secured to theflanged end 3'4 of the eccentric sleeve by rivets 51, or other suitablesecuring means. The weight will act as a counterbalance, and I havefound such a device to be an important adjunct to the practical use ofcompression ratio changing devices.

The term load appearing in the specification and' claims includes engineexplosion forces which are qualified by torque, for example in anaeroplane engine the torque is determined by the propellercharacteristics. 7

As the air density decreases with increased elevation, it is necessarywith present engines to increase the fuel quantity in the charges. withincreasing elevation in order to maintain a constant horse power. Thisinvention automatically maintains the air compressed in the cylinder ata constant density, within cruising elevational limits, and consequentlya constant horse power can be maintained with a uniform fuel chargeregardless of elevation. With the horse power and fuel quantity of thecharges thus maintained constant, the speed of the aeroplane propelledby an engine with this invention associated therewith will increasewhile elevating because the propeller load decreases.

The compression ratio structure above described is compactly associatedwith the engine, and has proven very useful for the purposes hereinpointed out.

Various changes can be made in the structure herein illustrated anddescribed without departing from the spirit of the invention and thescope of what is claimed.

What I claim is:

1. In an internal combustion engine, the combination with the enginecylinder, piston, crank shaft and crank, of an eccentric rotatablymounted on the crank, a connecting rod coupled to said piston andengagingsaid eccentric, the forces of explosion being transmitted to thecocentric through the rod in a direction tending to rotate the same, amember concentric with the crank shaft and connected to rotate with saideccentric, and means carried by the crank shaft including a coil springresisting the rotation of the rotatable member relative to the crankshaft. I

2. In an explosive engine, a crank shaft, an eccentric rotatable on thecrank shaft pin, a piston connecting rod engaging said eccentric, saideccentric being rotated relative to the crank shaft by explosion forcestransmitted through the rod, and resilient means carried by the crankshaft and associated with said eccentric absorbing vibration caused byexplosions.

3. The method of operating an internal combustion engine comprisingintroducing air charges into the cylinder, introducing fuel charges intothe cylinder, and regulating the compression ratio through explosionforces inversely to the engine load.

4. In a Diesel engine having a crank shaft, a plurality of cylinders, amovable wall associated with each cylinder to define therewith thebustion engine combustion space, and means connecting the walls with thecrank shaft and responsive to engine explosion forces to regulate thecompression ratio inversely with the variance of the crank shaft load.

.5. The method of operating an internal comcomprising introducing aircharges into the engine cylinders, introducing fuel charges into the aircharges in the cylinders, and automatically varying the compressionratio by the explosion forces inversely to the engine load above apredetermined amount.

6. The method of operating an internal combustion engine comprisingintroducing air charges into the engine cylinders, introducing fuelcharges into the air charges in the cylinders, and automatically varyingthe compression ratio by the engine explosion forces inversely with theengine load. 7

7. In an explosive engine, a crank shaft, a cylinder, a pistonreciprocable in the cylinder, mechanism connecting the piston with thecrank shaft including compression ratio changing mechanism, and meansassociated with the compression ratio changing mechanism for absorbingexplosion forces;

8. In an internal combustion engine, a cylinder into which air and fuelare introduced, a movable wall, said cylinder and said wall forming acombustion chamber, movable means connected with the wall adapted toregulate the capacity of the combustion chamber during the introductionof air, and adjustable means associated with the regulating means tocontrol its movement, said control means being automatically adjustablein response to explosion forces.

9. In an internal combustion engine, a cylinder into which air and fuelare introduced, a movable wall, said cylinder and said wall forming acombustion chamber,-movable means connected with the wall adapted toregulate the capacity of the combustion chamber during the introductionof air, adjustable means associated with the regulating means to controlthe movement thereof, said control means being automatically adjustablein response to the forces of explosions, and means associated with theadjustable means opposing the adjusting effect of ciated with theeccentric sleeve in a relation resisting the rotating effect of theexplosion forces. 35

11. In a Diesel engine, a crank shaft, a plurality' of cylinders inwhich air charges are compressed and commingled with fuel charges, amovable wall associated with each cylinder and defining therewith thecombustion chamber, and means connecting the walls with the crank shaft,said means being responsive to engine explosion forces to automaticallyregulate the compression ratio inversely to the torque of the crankshaft.

. 12. In an engine, a plurality of cylinders in which fuel mixtures arecompressed, a crank pin, pistons in the cylinders, a hub carried by thecrank pin, connecting rods between the hub and the pistons, andshiftable eccentric bearing means intermediate the hub and the crankpin, said bearing means being shifted on the crank pin in response toexplosion forces to automatically change the hub relation angularly ofthe crank pin.

13. In an engine, a plurality of cylinders in which fuel mixtures arecompressed,- a crank pin, pistons in the cylinders, a hub carried by thecrank pin, connecting rods between the hub and the pistons, shiftableeccentric bearing means intermediate the hub and the crank pin, saidhearing means being shifted on the crank pin in response to explosionforces to automatically change the hub relation angularly of the crankpin, and resilient means resisting movement of the bearin means from theexplosion forces.

14. In an internal combustion engine, a cylinder into which air isintroduced and compressed, a movable wall associated with the cylinderand forming therewith a combustion space, movable means connected withthe wall and adapted to vary the capacity of the combustion chamberduring the introduction of air, and adjustable mechanism includingspring means associated with the movable means, said mechanism beingadjustable in response to explosion forces.

15. In an aeronautical motor, cylinders having valve means through whichair is introduced, a movable wall associated with each cylinder, thecylinders and their associated movable walls defining combustion spacesinto which air and fuel charges are introduced, and means forautomatically changing the relation of the walls relative to thecylinders below a predetermined elevation and without increasing thequantity of the fuel charges to vary the capacity of the combustionspaces in accordance with elevation during the admission of air.-

16. In an aeronautical motor, cylinders having valve means through whichair is introduced, a movable wall associated with each cylinder, thecylinders and the walls defining combustion spaces into which aircharges and fuel charges are'introduced, and means responsive, below apredetermined elevation and without increasing.

the quantity of the fuel charges, to applied torque for automaticallychanging the relation of the walls relative to the cylinders to vary theair capacity of the combustion spaces inversely with air density duringthe intake of air.

LIONEL M. WOOLSON.

